Telecommunications apparatus and methods

ABSTRACT

A method of operating a terminal device and a base station in a wireless telecommunications system to communicate with one another using a primary component carrier operating on radio resources within a first frequency band and a secondary component carrier operating on radio resources within a second frequency band. The terminal device makes measurements of radio usage in the second frequency band, e.g. by other devices which are not part of the wireless telecommunications system but which can also use radio resources within the second frequency band. The terminal device transmits an indication of the measurements to the base station, and on the basis if this the base station establishes a configuration setting for the secondary component carrier, for example in terms of frequency resources to use for the secondary component carrier.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.16/986,261, filed Aug. 6, 2020, which is a continuation of U.S.application Ser. No. 16/173,850, filed Oct. 29, 2018 (now U.S. Pat. No.10,772,105), which is a continuation of U.S. application Ser. No.15/305,999, filed Oct. 21, 2016 (now U.S. Pat. No. 10,129,897), which isbased on PCT filing PCT/EP2015/061298, filed May 21, 2015, and claimspriority to European Patent Application 14171285.1, filed in theEuropean Patent Office on Jun. 5, 2014, the entire contents of all ofeach are incorporated herein by reference.

BACKGROUND Field

The present disclosure relates to mobile communications networks andmethods for communicating data using mobile communications networks,infrastructure equipment for mobile communications networks,communications devices for communicating data via mobile communicationsnetworks and methods of communicating via mobile communicationsnetworks.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

It is well known in the field of wireless telecommunications for regionsof the radio spectrum to be assigned to different mobile networkoperators (MNO) for their exclusive use through a license. A licensetypically grants an MNO exclusive use over a number of years of apredefined portion of the radio frequency spectrum in which to deploy amobile communications network (e.g. GSM, WCDMA/HSPA, LTE/LTE-A). As aresult of this approach, an operator has guarantees of no other radioservices interfering with the radio resources that have been assigned tothe operator, and within the limitations of the license conditions ithas exclusive control over what radio technology it deploys in thenetwork. Consequently, a wireless telecommunications system that isprimarily designed to operate using radio resources that have beenlicensed for exclusive use by the wireless telecommunications system canoperate with a degree of centralised control and coordination to helpmake most efficient use of the available radio resources. Such awireless telecommunication system also manages all the interferenceinternally, based on standard specifications, since the license grantsit good immunity from external interference sources. Coexistence ofdifferent devices deployed on an MNO's licensed band is managed throughconformance to relevant radio standards. Licensed spectrum is todayusually assigned to operators via government-organised auctions, butso-called “beauty contests” continue also to be in use.

It is also well known in the field of wireless telecommunications forregions of the available radio spectrum to remain unlicensed. Unlicensed(license exempt) radio spectrum may, at least to some extent, be freelyused by a number of different technologies, such as Wi-Fi and Bluetoothand other non-3GPP radio access technologies. Operating parameters fordevices using unlicensed spectrum bands are typically stipulated bytechnical regulatory requirements such as e.g. the FCC Part 15 rule for2.4 GHz ISM band. Coexistence of different devices deployed onunlicensed band, due to the lack of centralised coordination andcontrol, is usually based on such technical rules and various politenessprotocols.

The use of wireless telecommunications system technologies designed foroperation on licensed radio spectrum, such as LTE, is becoming more andmore prevalent, both in terms of increasing take-up of established usesfor wireless telecommunications technologies, and also the introductionof new uses, e.g., in the developing field of machine-typecommunications (MTC). In order to help provide more bandwidth to supportthis increased use of wireless telecommunications technologies, it hasrecently been proposed to use unlicensed radio spectrum resources tosupport operations on licensed radio spectrum.

However, in contrast to licensed spectrum, unlicensed spectrum can beshared and used among different technologies, or different networksusing the same technology, without any co-ordinated/centralised control,for example to provide protection against interference. As a consequenceof this, the use of wireless technologies in unlicensed spectrum can besubject to unpredictable interference and has no guarantees of spectrumresources, i.e. the radio connection takes place on a best effort basis.This means that wireless network technologies, such as LTE, which aregenerally designed to operate using licensed radio resources, requiremodified approaches to allow them to efficiently use unlicensed radioresources, and in particular to co-exist reliably and fairly with otherradio access technologies that may be simultaneously operating in theunlicensed spectrum band.

Therefore, deploying a mobile radio access technology system primarilydesigned to operate in licensed spectrum bands (i.e. having exclusiveaccess to, and hence a level of control over, the relevant radioresources) in a manner which is required by operation in unlicensedspectrum bands (i.e. without having exclusive access to at least some ofthe relevant radio resources), gives rise to new technical challenges.

SUMMARY

According to an aspect of the disclosure there is provided a method ofoperating a terminal device in a wireless telecommunications system forcommunicating with network infrastructure equipment using a primarycomponent carrier operating on radio resources within a first frequencyband and a secondary component carrier operating on radio resourceswithin a second frequency band, wherein the method comprises the steps:(a) receiving an indication of a configuration setting for the secondarycomponent carrier from the network infrastructure equipment; (b)establishing a validity period for the configuration setting for thesecondary component carrier; and (c) receiving data from the networkinfrastructure equipment using the primary component carrier and thesecondary component carrier operating in accordance with theconfiguration setting for the secondary component carrier during thevalidity period for the configuration setting.

According to another aspect of the disclosure there is provided aterminal device for use in a wireless telecommunications system forcommunicating with network infrastructure equipment using a primarycomponent carrier operating on radio resources within a first frequencyband and a secondary component carrier operating on radio resourceswithin a second frequency band, wherein the terminal device comprises acontroller unit and a transceiver unit configured to operate togetherto: (a) receive an indication of a configuration setting for thesecondary component carrier from the network infrastructure equipment;(b) establish a validity period for the configuration setting for thesecondary component carrier; and (c) receive data from the networkinfrastructure equipment using the primary component carrier and thesecondary component carrier operating in accordance with theconfiguration setting for the secondary component carrier during thevalidity period for the configuration setting.

According to another aspect of the disclosure there is providedcircuitry for a terminal device for use in a wireless telecommunicationssystem for communicating with network infrastructure equipment using aprimary component carrier operating on radio resources within a firstfrequency band and a secondary component carrier operating on radioresources within a second frequency band, wherein the circuitrycomprises a controller element and a transceiver element configured tooperate together to: (a) receive an indication of a configurationsetting for the secondary component carrier from the networkinfrastructure equipment; (b) establish a validity period for theconfiguration setting for the secondary component carrier; and (c)receive data from the network infrastructure equipment using the primarycomponent carrier and the secondary component carrier operating inaccordance with the configuration setting for the secondary componentcarrier during the validity period for the configuration setting.

According to another aspect of the disclosure there is provided a methodof operating network infrastructure equipment in a wirelesstelecommunications system for communicating with a terminal device usinga primary component carrier operating on radio resources within a firstfrequency band and a secondary component carrier operating on radioresources within a second frequency band, wherein the method comprisesthe steps: (a) establishing an indication of radio usage in the secondfrequency band; (b) determining a configuration setting for thesecondary component carrier based on the indication of radio usage inthe second frequency band; (d) establishing a validity period for theconfiguration setting for the secondary component carrier; (e)transmitting an indication of the configuration setting for thesecondary component carrier to the terminal device; (f) transmittingdata to the terminal device using the primary component carrier and thesecondary component carrier operating in accordance with theconfiguration setting for the secondary component carrier during thevalidity period for the configuration setting; and (g) determining ifthe validity period for the configuration setting for the secondarycomponent carrier has expired, and if so, repeating steps (a) and (b).

According to another aspect of the disclosure there is provided networkinfrastructure equipment for use in a wireless telecommunications systemfor communicating with a terminal device using a primary componentcarrier operating on radio resources within a first frequency band and asecondary component carrier operating on radio resources within a secondfrequency band, wherein the network infrastructure equipment comprises acontroller unit and a transceiver unit configured to operate togetherto: (a) establish an indication of radio usage in the second frequencyband; (b) determine a configuration setting for the secondary componentcarrier based on the indication of measurements of radio usage in thesecond frequency band; (d) establish a validity period for theconfiguration setting for the secondary component carrier; (e) transmitan indication of the configuration setting for the secondary componentcarrier to the terminal device; (f) transmit data to the terminal deviceusing the primary component carrier and the secondary component carrieroperating in accordance with the configuration setting for the secondarycomponent carrier during the validity period for the configurationsetting; and (g) determine if the validity period for the configurationsetting for the secondary component carrier has expired, and if so, toagain receive from the terminal device an indication of measurements ofradio usage in the second frequency band made by the terminal device anddetermine a configuration setting for the secondary component carrierbased on the received measurements of radio usage in the secondfrequency band.

According to another aspect of the disclosure there is providedcircuitry for network infrastructure equipment for use in a wirelesstelecommunications system for communicating with a terminal device usinga primary component carrier operating on radio resources within a firstfrequency band and a secondary component carrier operating on radioresources within a second frequency band, wherein the circuitrycomprises a controller element and a transceiver element configured tooperate together to: (a) establish an indication of measurements ofradio usage in the second frequency band; (b) determine a configurationsetting for the secondary component carrier based on the indication ofmeasurements of radio usage in the second frequency band; (d) establisha validity period for the configuration setting for the secondarycomponent carrier; (e) transmit an indication of the configurationsetting for the secondary component carrier to the terminal device; (f)transmit data to the terminal device using the primary component carrierand the secondary component carrier operating in accordance with theconfiguration setting for the secondary component carrier during thevalidity period for the configuration setting; and (g) determine if thevalidity period for the configuration setting for the secondarycomponent carrier has expired, and if so, to again receive from theterminal device an indication of measurements of radio usage in thesecond frequency band made by the terminal device and determine aconfiguration setting for the secondary component carrier based on thereceived measurements of radio usage in the second frequency band.

Further respective aspects and features are defined by the appendedclaims.

The foregoing paragraphs have been provided by way of generalintroduction, and are not intended to limit the scope of the followingclaims. The described embodiments, together with further advantages,will be best understood by reference to the following detaileddescription taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 provides a schematic diagram illustrating an example of a mobiletelecommunication system;

FIG. 2 provides a schematic diagram illustrating a LTE radio frame;

FIG. 3 provides a schematic diagram illustrating an example of a LTEdownlink radio subframe;

FIG. 4 schematically represents a wireless telecommunications systemaccording to an embodiment of the disclosure; and

FIG. 5 is a signalling ladder diagrams representing communicationsbetween a base station and a terminal device operating in accordancewith some embodiments of the disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 provides a schematic diagram illustrating some basicfunctionality of a mobile telecommunications network/system 100operating in accordance with LTE principles and which may be adapted toimplement embodiments of the disclosure as described further below.Various elements of FIG. 1 and their respective modes of operation arewell-known and defined in the relevant standards administered by the3GPP® body, and also described in many books on the subject, forexample, Holma H. and Toskala A [1]. It will be appreciated thatoperational aspects of the telecommunications network which are notspecifically described below may be implemented in accordance with anyknown techniques, for example according to the relevant standards.

The network 100 includes a plurality of base stations 101 connected to acore network 102. Each base station provides a coverage area 103 (i.e. acell) within which data can be communicated to and from terminal devices104. Data is transmitted from base stations 101 to terminal devices 104within their respective coverage areas 103 via a radio downlink. Data istransmitted from terminal devices 104 to the base stations 101 via aradio uplink. The uplink and downlink communications are made usingradio resources that are licensed for use by the operator of the network100. The core network 102 routes data to and from the terminal devices104 via the respective base stations 101 and provides functions such asauthentication, mobility management, charging and so on. Terminaldevices may also be referred to as mobile stations, user equipment (UE),user terminal, mobile radio, and so forth. Base stations may also bereferred to as transceiver stations/nodeBs/e-nodeBs, and so forth.

Mobile telecommunications systems such as those arranged in accordancewith the 3GPP defined Long Term Evolution (LTE) architecture use anorthogonal frequency division modulation (OFDM) based interface for theradio downlink (so-called OFDMA) and a single carrier frequency divisionmultiple access scheme (SC-FDMA) on the radio uplink. FIG. 2 shows aschematic diagram illustrating an OFDM based LTE downlink radio frame201. The LTE downlink radio frame is transmitted from a LTE base station(known as an enhanced Node B) and lasts 10 ms. The downlink radio framecomprises ten subframes, each subframe lasting 1 ms. A primarysynchronisation signal (PSS) and a secondary synchronisation signal(SSS) are transmitted in the first and sixth subframes of the LTE frame.A physical broadcast channel (PBCH) is transmitted in the first subframeof the LTE frame.

FIG. 3 is a schematic diagram of a grid which illustrates the structureof an example conventional downlink LTE subframe. The subframe comprisesa predetermined number of symbols which are transmitted over a 1 msperiod. Each symbol comprises a predetermined number of orthogonalsubcarriers distributed across the bandwidth of the downlink radiocarrier.

The example subframe shown in FIG. 3 comprises 14 symbols and 1200subcarriers spread across a 20 MHz bandwidth licensed for use by theoperator of the network 100, and this example is the first subframe in aframe (hence it contains PBCH). The smallest allocation of physicalresource for transmission in LTE is a resource block comprising twelvesubcarriers transmitted over one subframe. For clarity, in FIG. 3, eachindividual resource element is not shown, instead each individual box inthe subframe grid corresponds to twelve subcarriers transmitted on onesymbol.

FIG. 3 shows in hatching resource allocations for four LTE terminals340, 341, 342, 343. For example, the resource allocation 342 for a firstLTE terminal (UE 1) extends over five blocks of twelve subcarriers (i.e.60 subcarriers), the resource allocation 343 for a second LTE terminal(UE2) extends over six blocks of twelve subcarriers (i.e. 72subcarriers), and so on.

Control channel data can be transmitted in a control region 300(indicated by dotted-shading in FIG. 3) of the subframe comprising thefirst “n” symbols of the subframe where “n” can vary between one andthree symbols for channel bandwidths of 3 MHz or greater and where “n”can vary between two and four symbols for a channel bandwidth of 1.4MHz. For the sake of providing a concrete example, the followingdescription relates to host carriers with a channel bandwidth of 3 MHzor greater so the maximum value of “n” will be 3 (as in the example ofFIG. 3). The data transmitted in the control region 300 includes datatransmitted on the physical downlink control channel (PDCCH), thephysical control format indicator channel (PCFICH) and the physical HARQindicator channel (PHICH). These channels transmit physical layercontrol information. Control channel data can also or alternatively betransmitted in a second region of the subframe comprising a number ofsubcarriers for a time substantially equivalent to the duration of thesubframe, or substantially equivalent to the duration of the subframeremaining after the “n” symbols. The data transmitted in this secondregion is transmitted on the enhanced physical downlink control channel(EPDCCH). This channel transmits physical layer control informationwhich may be in addition to that transmitted on other physical layercontrol channels.

PDCCH and EPDCCH contain control data indicating which subcarriers ofthe subframe have been allocated to specific terminals (or all terminalsor subset of terminals). This may be referred to as physical-layercontrol signalling/data. Thus, the PDCCH and/or EPDCCH data transmittedin the control region 300 of the subframe shown in FIG. 3 would indicatethat UE1 has been allocated the block of resources identified byreference numeral 342, that UE2 has been allocated the block ofresources identified by reference numeral 343, and so on.

PCFICH contains control data indicating the size of the control region(i.e. between one and three symbols for channel bandwidths of 3 MHz orgreater and between two and four symbols for channel bandwidths of 1.4MHz).

PHICH contains HARQ (Hybrid Automatic Request) data indicating whetheror not previously transmitted uplink data has been successfully receivedby the network.

Symbols in a central band 310 of the time-frequency resource grid areused for the transmission of information including the primarysynchronisation signal (PSS), the secondary synchronisation signal (SSS)and the physical broadcast channel (PBCH). This central band 310 istypically 72 subcarriers wide (corresponding to a transmission bandwidthof 1.08 MHz). The PSS and SSS are synchronisation signals that oncedetected allow a LTE terminal device to achieve frame synchronisationand determine the physical layer cell identity of the enhanced Node Btransmitting the downlink signal. The PBCH carries information about thecell, comprising a master information block (MIB) that includesparameters that LTE terminals use to properly access the cell. Datatransmitted to terminals on the physical downlink shared channel(PDSCH), which may also be referred to as a downlink data channel, canbe transmitted in other resource elements of the subframe. In generalPDSCH conveys a combination of user-plane data and non-physical layercontrol-plane data (such as Radio Resource Control (RRC) and Non AccessStratum (NAS) signalling). The user-plane data and non-physical layercontrol-plane data conveyed on PDSCH may be referred to as higher layerdata (i.e. data associated with a layer higher than the physical layer).

FIG. 3 also shows a region of PDSCH containing system information andextending over a bandwidth of R344. A conventional LTE subframe willalso include reference signals which are not shown in FIG. 3 in theinterests of clarity.

The number of subcarriers in a LTE channel can vary depending on theconfiguration of the transmission network. Typically this variation isfrom 72 sub carriers contained within a 1.4 MHz channel bandwidth to1200 subcarriers contained within a 20 MHz channel bandwidth (asschematically shown in FIG. 3). As is known in the art, data transmittedon the PDCCH, PCFICH and PHICH is typically distributed on thesubcarriers across the entire bandwidth of the subframe to provide forfrequency diversity.

The communications between the base stations 101 and the terminaldevices 104 are conventionally made using radio resources that have beenlicensed for exclusive use by the operator of the network 100. Theselicensed radio resources will be only a portion of the overall radiospectrum. Other devices within the environment of the network 100 may bewirelessly communicating using other radio resources. For example, adifferent operators network may be operating within the samegeographical region using different radio resources that have beenlicensed for use by the different operator. Other devices may beoperating using other radio resources in an unlicensed radio spectrumband, for example using Wi-Fi or Bluetooth technologies.

As noted above, it has been proposed that a wireless telecommunicationsnetwork using radio resources in a licensed portion of the radiospectrum might be supported by using radio resources in an unlicensedportion of the radio spectrum (i.e. a portion of the radio spectrum overwhich the wireless telecommunications network does not have exclusiveaccess, but rather which is shared by other access technologies and/orother wireless telecommunications networks). In particular, it has beenproposed that carrier aggregation based techniques may be used to allowunlicensed radio resources to be used in conjunction with licensed radioresources.

In essence, carrier aggregation allows for communications between a basestation and a terminal device to be made using more than one carrier.This can increase the maximum data rate that may be achieved between abase station and a terminal device as compared to when using only onecarrier and can help enable more efficient and productive use offragmented spectrum. Individual carriers that are aggregated arecommonly referred to as component carriers (or sometimes simplycomponents). In the context of LTE, carrier aggregation was introducedin Release 10 of the standard. In accordance with the current standardsfor carrier aggregation in an LTE-based system, up to five componentcarriers can be aggregated for each of downlink and uplink. Thecomponent carriers are not required to be contiguous with one anotherand can have a system bandwidth corresponding to any of the LTE-definedvalues (1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz), therebyallowing a total bandwidth of up to 100 MHz. Of course it will beappreciated this is just one example of a specific carrier aggregationimplementation and other implementations may allow for different numbersof component carriers and/or bandwidths.

Further information on the operation of carrier aggregation in thecontext of LTE-based wireless telecommunications systems can be found inthe relevant standards documents, such as ETSI TS 136 211 V11.5.0(2014-01)/3GPP TS 36.211 version 11.5.0 Release 11 [2], ETSI TS 136 212V11.4.0 (2014-01)/3GPP TS 36.212 version 11.4.0 Release 11 [3]; ETSI TS136 213 V11.6.0 (2014-03)/3GPP TS 36.213 version 11.6.0 Release 11 [4];ETSI TS 136 321 V11.5.0 (2014-03)/3GPP TS 36.321 version 11.5.0 Release11 [5]; and ETSI TS 136 331 V11.7.0 (2014-03)/3GPP TS 36.331 version11.7.0 Release 11 [6].

In accordance with the terminology and implementation used for carrieraggregation in the context of an LTE-based system, a cell is denoted the‘primary cell’, or Pcell, for a terminal device if it is the cell thatis initially configured during connection setup for the terminal device.Thus the primary cell handles RRC (radio resource control) connectionestablishment/re-establishment for the terminal device. The primary cellis associated with a downlink component carrier and an uplink componentcarrier (CoC). These may sometimes be referred to herein as primarycomponent carriers. A cell that is configured for use by the terminaldevice after initial connection establishment on the Pcell is termed a‘secondary cell’, or Scell. Thus the secondary cells are configuredafter connections establishment to provide additional radio resources.The carriers associated with Scells may sometimes be referred to hereinas secondary component carriers. Since in LTE up to five componentcarriers can be aggregated, up to four Scells (correspondinglyassociated with up to four secondary component carriers) can beconfigured for aggregation with the primary cell (associated with theprimary component carrier). An Scell might not have both a downlink anduplink component carrier and the association between uplink componentcarriers and downlink component carriers is signalled in SIB2 on eachdownlink component carrier. The primary cell supports PDCCH and PDSCH ondownlink and PUSCH and PUCCH on uplink whereas the secondary cell(s)support PDCCH and PDSCH on downlink and PUSCH on uplink, but not PUCCH.Measurement and mobility procedures are handled on the Pcell and thePcell cannot be de-activated. The Scell(s) may be dynamically activatedand deactivated, for example according to traffic needs, though MAClayer signalling to the terminal device. An Scells for a terminal devicemay also be deactivated automatically (time out) if the terminal devicedoes not receive any transmission resource allocations on the Scell fora threshold amount of time.

Some aspects of physical layer control signalling for an LTE-basedimplementation of carrier aggregation based on the current standards arenow described.

Each downlink component carrier has the normal LTE control channels:(E)PDCCH, PCFICH and PHICH. However, carrier aggregation introduces thepossibility of so-called cross-carrier scheduling (XCS) on PDCCH. Tosupport cross-carrier scheduling, a downlink control information (DCI)message on PDCCH includes a carrier indicator field (CIF) comprisingthree bits to indicate which of the component carriers the PDCCH messageapplies to. If there is no CIF, the PDCCH is treated as applying to thecarrier on which it is received. A motivation for providingcross-carrier scheduling primarily applies for heterogeneous network(het-net) scenarios where overlaid macro- and small-cells may operatecarrier aggregation in the same band. The effects of interferencebetween the respective macro- and small-cells' PDCCH signalling can bemitigated by having the macro-cell transmit its PDCCH signalling on onecomponent carrier at relatively high transmit power (to provide coverageacross the macro-cell), while the small-cells use an alternativecomponent carrier for their PDCCH scheduling.

The control region supporting PDCCH may differ in size (i.e. number ofOFDM symbols) between component carriers, so they can carry differentPCFICH values. However, the potential for interference in the controlregion in a het-net implementation may mean that PCFICH cannot bedecoded on a particular component carrier. Therefore, current LTEstandards allow for each component to carrier a semi-static indicationof which OFDM symbol PDSCH can be assumed to begin in each subframe. Iffewer OFDM symbols are actually used for the control region, thefree/spare OFDM symbol(s) may be used for PDSCH transmissions toterminal devices which are not being cross-carrier scheduled as theywill decode the actual PCFICH. If more OFDM symbols actually used forthe control region, there will be some degree of performance degradationfor the cross-carrier scheduled terminal devices.

PHICH signalling is sent on the downlink component carrier that sent thePDCCH signalling containing the PUSCH allocation to which the PHICHsignalling relates. Accordingly, one downlink component carrier maycarry PHICH for more than one component carrier.

In the uplink, the basic operation of PUCCH is not altered by theintroduction of carrier aggregation. However, a new PUCCH format (format3) is introduced to support the sending of acknowledgement signalling(ACK/NACK signalling) for multiple downlink component carriers, and withsome alterations to format 1b to increase the number of ACK/NACK bits itcan carry.

In current LTE-based carrier aggregation scenarios, primary andsecondary synchronisation signalling (PSS and SSS) are transmitted onall component carriers using the same physical-layer cell identity (PCI)and component carriers are all synchronised with one another. This canhelp with cell search and discovery procedures. Issues relating tosecurity and system information (SI) are handled by the Pcell. Inparticular, when activating an Scell, the Pcell delivers the relevant SIfor the Scell to the terminal device using dedicated RRC signalling. Ifthe system information relating to a Scell changes, the Scell isreleased and re-added by Pcell RRC signalling (in one RRC message).Pcell changes, e.g. due to long-term fluctuations in channel qualityacross the Pcell bandwidth, are handled using a modified handoverprocedure. The source Pcell passes all the relevant carrier aggregation(CA) information to the target Pcell so the terminal device can begin touse all the assigned component carriers when handover is complete.

Random access procedures are primarily handled on the uplink componentcarrier of Pcell for a terminal device, although some aspects ofcontention resolution signalling may be cross-carrier scheduled toanother serving cell (i.e. an Scell).

As noted above, carrier aggregation is one approach for making use ofunlicensed radio spectrum resources in wireless communication networkswhich are primarily designed to use licensed radio spectrum. In broadsummary, a carrier aggregation based approach may be used to configureand operate a first component carrier (e.g. a primary component carrierassociated with a Pcell in LTE terminology) within a region of the radiospectrum that has been licensed for use by a wireless telecommunicationsnetwork, and to also configure and operate one or more further componentcarriers (e.g. a secondary component carrier associated with an Scell inLTE terminology) in an unlicensed region of the radio spectrum. Thesecondary component carrier(s) operating in the unlicensed region of theradio spectrum may do so in an opportunistic manner by making use of theunlicensed radio resources when they are available. There may also beprovisions made for restricting the extent to which a given operator canmake use of the unlicensed radio resources, for example by defining whatmight be referred to as politeness protocols.

Although known carrier aggregation schemes can form a basis for usingunlicensed radio spectrum resources (or other forms of shared radioresources) in conjunction with licensed radio spectrum resources, somemodifications to known carrier aggregation techniques may be appropriateto help optimise performance. This is because radio interference in theunlicensed radio spectrum can be expected to be subject to a wider rangeof unknown and unpredictable variations in time and frequency than mightbe seen within a region of the radio spectrum which has been licensedfor use by a particular wireless applications system. For a givenwireless telecommunications system operating in accordance with a giventechnology, such as LTE-A, interference in the unlicensed radio spectrummay arise from other systems operating quantity same technology, orsystems operating according to different technologies, such as Wi-Fi orBluetooth.

FIG. 4 schematically shows a telecommunications system 400 according toan embodiment of the disclosure. The telecommunications system 400 inthis example is based broadly on a LTE-type architecture. As such manyaspects of the operation of the telecommunications system 400 arestandard and well understood and not described here in detail in theinterest of brevity. Operational aspects of the telecommunicationssystem 400 which are not specifically described herein may beimplemented in accordance with any known techniques, for exampleaccording to the established LTE-standards and known variations thereof.

The telecommunications system 400 comprises a core network part (evolvedpacket core) 402 coupled to a radio network part. The radio network partcomprises a base station (evolved-nodeB) 404, a first terminal device406 and a second terminal device 408. It will of course be appreciatedthat in practice the radio network part may comprise a plurality of basestations serving a larger number of terminal devices across variouscommunication cells. However, only a single base station and twoterminal devices are shown in FIG. 4 in the interests of simplicity.

Although not part of the telecommunications system 400 itself, alsoshown in FIG. 4 are some other devices which are operable to wirelesslycommunicate with one another and which are operating within the radioenvironment of the telecommunications system 400. In particular, thereis a pair of wireless access devices 416 communicating with one anothervia radio link 418 operating in accordance with a Wi-Fi standard and apair of Bluetooth devices 420 communicating with one another via radiolink 422 operating in accordance with a Bluetooth standard. These otherdevices represent a potential source of radio interference for thetelecommunications system 400. It will be appreciated that in practicethere will typically be many more such devices operating in the radioenvironment of the wireless telecommunications system 400, and only twopairs of devices 416, 418 are shown in FIG. 4 for simplicity.

As with a conventional mobile radio network, the terminal devices 406,408 are arranged to wirelessly communicate data to and from the basestation (transceiver station) 404. The base station is in turncommunicatively connected to a serving gateway, S-GW, (not shown) in thecore network part which is arranged to perform routing and management ofmobile communications services to the terminal devices in thetelecommunications system 400 via the base station 404. In order tomaintain mobility management and connectivity, the core network part 402also includes a mobility management entity (not shown) which manages theenhanced packet service, EPS, connections with the terminal devices 406,408 operating in the communications system based on subscriberinformation stored in a home subscriber server, HSS. Other networkcomponents in the core network (also not shown for simplicity) include apolicy charging and resource function, PCRF, and a packet data networkgateway, PDN-GW, which provides a connection from the core network part402 to an external packet data network, for example the Internet. Asnoted above, the operation of the various elements of the communicationssystem 400 shown in FIG. 4 may be broadly conventional apart from wheremodified to provide functionality in accordance with embodiments of thedisclosure as discussed herein.

The terminal devices 406, 408 each comprise a transceiver unit 406 a,408 a for transmission and reception of wireless signals and acontroller unit 406 b, 408 b configured to control the operation of therespective devices 406, 408 in accordance with embodiments of thedisclosure. The respective controller units 406 b, 408 b may eachcomprise a processor unit which is suitably configured/programmed toprovide the desired functionality described herein using conventionalprogramming/configuration techniques for equipment in wirelesstelecommunications systems. For each of the terminal devices 406, 408,their respective transceiver units 406 a, 408 a and controller units 406b, 408 b are schematically shown in FIG. 4 as separate elements for easeof representation. However, it will be appreciated that for eachterminal device the functionality of these units can be provided invarious different ways, for example using a single suitably programmedgeneral purpose computer, or suitably configured application-specificintegrated circuit(s)/circuitry, or using a plurality of discretecircuitry/processing elements for providing different elements of thedesired functionality. It will be appreciated the terminal devices 406,408 will in general comprise various other elements associated withtheir operating functionality in accordance with established wirelesstelecommunications techniques (e.g. a power source, possibly a userinterface, and so forth).

As has become commonplace in the field of wireless telecommunications,terminal devices may support Wi-Fi and Bluetooth functionality inaddition to cellular/mobile telecommunications functionality. Thus thetransceiver units 406 a, 408 a of the respective terminal devices maycomprise functional modules operable according to different wirelesscommunications operating standards. For example, the terminal devices'transceiver units may each comprise an LTE transceiver module forsupporting wireless communications in accordance with an LTE-basedoperating standard, a WLAN transceiver module for supporting wirelesscommunications in accordance with a WLAN operating standard (e.g. aWi-Fi standard), and a Bluetooth transceiver module for supportingwireless communications in accordance with a Bluetooth operatingstandard. The underlying functionality of the different transceivermodules may be provided in accordance with conventional techniques. Forexample, a terminal device may have separate hardware elements toprovide the functionality of each transceiver module, or alternatively,a terminal device might comprise at least some hardware elements whichare configurable to provide some or all functionality of multipletransceiver modules. Thus the transceiver units 406 a, 408 a of theterminal devices 406, 408 represented in FIG. 4 are assumed here toprovide the functionality of an LTE transceiver module, a Wi-Fitransceiver module and a Bluetooth transceiver module in accordance withconventional wireless communications techniques.

The base station 404 comprises a transceiver unit 404 a for transmissionand reception of wireless signals and a controller unit 404 b configuredto control the base station 404. The controller unit 404 b may comprisea processor unit which is suitably configured/programmed to provide thedesired functionality described herein using conventionalprogramming/configuration techniques for equipment in wirelesstelecommunications systems. The transceiver unit 404 a and thecontroller unit 404 b are schematically shown in FIG. 4 as separateelements for ease of representation. However, it will be appreciatedthat the functionality of these units can be provided in variousdifferent ways, for example using a single suitably programmed generalpurpose computer, or suitably configured application-specific integratedcircuit(s)/circuitry or using a plurality of discretecircuitry/processing elements for providing different elements of thedesired functionality. It will be appreciated the base station 404 willin general comprise various other elements associated with its operatingfunctionality. For example, the base station 404 will in generalcomprise a scheduling entity responsible for scheduling communications.The functionality of the scheduling entity may, for example, be subsumedby the controller unit 404 b.

Thus, the base station 404 is configured to communicate data with thefirst and second terminal devices 406, 408 over respective first andsecond radio communication links 410, 412. The wirelesstelecommunications system 400 supports a carrier aggregation mode ofoperation in which the first and second radio communication links 410,412 each comprise a wireless access interface provided by multiplecomponent carriers. For example, each radio communication link maycomprise a primary component carrier and one or more secondary componentcarriers. Furthermore, the elements comprising the wirelesstelecommunications system 400 in accordance with this embodiment of thedisclosure are assumed to support carrier aggregation in an unlicensedspectrum mode. In this unlicensed spectrum mode the base stationcommunicates with terminal devices using a primary component carrieroperating on radio resources within a first frequency band that has beenlicensed for use by the wireless telecommunications system and one ormore secondary component carriers operating on radio resources within asecond frequency band that has not been licensed for exclusive use bythe wireless telecommunications system. The first frequency band maysometimes be referred to herein as a licensed frequency band and thesecond frequency band may sometimes be referred to herein as anunlicensed (U) frequency band. In the context of an LTE-based wirelesstelecommunications system, such as that represented in FIG. 4, operationin the unlicensed frequency band may be referred to as an LTE-U mode ofoperation. The first (licensed) frequency band may be referred to as anLTE band (or more particularly an LTE-A band) and the second(unlicensed) frequency band may be referred to as an LTE-U band.Resources on the LTE-U band may be referred to as U-resources. Aterminal device able to make use of U-resources may be referred to as aU-terminal device (or U-UE). More generally, the qualifier “U” may beused herein to conveniently identify operations in respect of theunlicensed frequency band.

It will be appreciated that the use of carrier aggregation techniquesand the use of unlicensed spectrum resources (i.e. resources that may beused by other devices without centralised coordination) in accordancewith embodiments of the disclosure may be based generally on previouslyproposed principles for such modes of operation, for example asdiscussed above, but with modifications as described herein to provideadditional functionality in accordance with embodiments of the presentdisclosure. Accordingly, aspects of the carrier aggregation andunlicensed spectrum operation which are not described in detail hereinmay be implemented in accordance with known techniques.

Modes of operation for the wireless telecommunications network 400represented in FIG. 4 in accordance with certain embodiments of thedisclosure will now be described. The general scenario for theseembodiments is assumed to be one in which a carrier aggregation capableterminal device is operating in an LTE-A cell as normal, and the basestation determines that it should configure the LTE-U capable terminaldevice with an additional aggregated carrier using LTE-U resources. Thespecific reason why the base station determines that it should configurea particular terminal device for LTE-U based carrier aggregation is notsignificant. Thus the LTE-A carrier provides a Pcell for the terminaldevice and the LTE-U resources provide one or more Scell(s) for theterminal device. It will be appreciated the LTE-A resources may also beused to provide component carriers associated with one or more furtherScells(s) in accordance with conventional carrier aggregationtechniques. For the examples described with reference to FIG. 4, theLTE-A transmissions in the licensed frequency band and the LTE-Utransmissions in the unlicensed frequency band, and thus the Pcell andScell(s), are both made from the same base station 404, but this may notbe the case in other example embodiments. The LTE-U carrier could ingeneral be utilised with a TDD (time division duplex) or FDD (frequencydivision duplex) frame structure. However, a consequence of some aspectsof existing regulatory restrictions on unlicensed spectrum usage in someregions means that TDD or downlink-only FDD operation may, at leastcurrently, be more likely.

FIG. 5 is a signalling ladder diagram schematically representing modesof operation for one of the terminal devices (UEs) 406, 408 and the basestation (eNB) 404 schematically represented in FIG. 4. The operation isfor communicating using a primary component carrier (associated with aprimary cell) operating on radio resources within a first frequency bandand a secondary component carrier (associated with a secondary cell)operating on radio resources within a second frequency band inaccordance with certain embodiments of the present disclosure. Asdiscussed above, the first frequency band is taken to correspond withresources that have been licensed for dedicated use by the operator ofthe wireless telecommunications system 400 whereas the second frequencyband is taken to correspond with resources that are shared by otherwireless communication technologies, and in particular in this exampleby Wi-Fi. In broad summary, some embodiments of the disclosure introducethe concept of a validity period for a configuration setting for asecondary carrier in the context of carrier aggregation using radioresources that are shared between different network operators and/orwireless access technologies.

The operation represented in FIG. 5 is generally iterative and is shownstarting from a stage at which the terminal device is configured foroperation on the primary cell associated with the primary carrier, butis not yet configured for operation on the secondary cell associatedwith the secondary carrier. This may be, for example, because theterminal device has only just connected to the primary cell or because aprevious secondary cell configuration is no longer valid.

In step S1 the terminal device makes measurements of radio usage in thesecond frequency band in its environment. In particular, the terminaldevice measures the degree of radio usage at different frequenciesacross the second frequency band. For example, the terminal device mayuse its WLAN transceiver module to scan for activity associated withother wireless communication devices, for example, Wi-Fi access points.From this the terminal device may establish, for example, an indicationof frequency resources used by other wireless communications devicesand/or an indication of a received signal strength for wirelesscommunications associated with other wireless communications devicesand/or an indication of an identifier for the other wirelesscommunications device (e.g. SSID). The terminal device may also scan forradio usage in the second frequency band by other devices operatingaccording to other operating standards, for example Bluetooth and/orother LTE networks. In some embodiments the terminal device might notseparately measure radio usage by different technologies, but may simplymeasure an aggregate level of radio signals (which may include radionoise) in its environment at different frequencies across the secondfrequency band.

In step S2 the terminal device transmits an indication of themeasurements of radio usage at different frequencies across the secondfrequency band to the base station. This may be done on uplink radioresources on the already-configured primary cell to which the terminaldevice is connected in accordance with conventional signallingtechniques, for example in accordance with the established principles ofmeasurement report RRC signalling.

In Step S3, the base station determines a configuration setting for thesecondary component carrier based on the received measurements of radiousage in the second frequency band. For example, the configurationsetting may define transmission resources (e.g. in terms of time and/orfrequency resources) selected from within the second frequency band touse for the secondary component carrier.

The base station may determine appropriate transmission resources forthe secondary cell configuration from the received measurements of radiousage in accordance with any established techniques for selectingappropriate transmission resources to use in a competitive(opportunistic) radio environment based on measurements of existingusage. For example, the base station may avoid transmission resources inregions of the second frequency band for which the terminal devicemeasurement reports indicate a relatively high degree of radio usage,and may instead preferentially select a configuration for the secondarycarrier that makes use of transmission resources in spectral regionshaving a relatively low degree of radio usage.

In step S4 the base station transmits an indication of the chosenconfiguration setting for the secondary carrier to the terminal device.This may be done on downlink radio resources on the already-configuredprimary cell in accordance with conventional signalling techniques, forexample in accordance with the established principles of radio bearer(re)configuration message RRC signalling.

In step S5 the terminal device configures its transceiver unit (and inparticular the LTE transceiver module component of its transceiver unit)in accordance with the configuration setting information received fromthe base station, for example by appropriate tuning of the transceivercircuitry. This may be formed in accordance with conventional techniquesfor radio bearer configuration setting.

In step S6 the terminal device establishes a validity period for theconfiguration setting for the secondary carrier received in step S4 andstarts a corresponding validity timer. The validity period is a timeduration for which the configuration setting is to be assumed to bevalid, thereby providing for a semi-static/semi-persistent secondarycell configuration. The duration of the validity period for theconfiguration setting may in some cases be fixed. For example, theduration of the validity period may be defined in an operating standardfor the wireless telecommunications system, for example based onregulatory agreements between different operators and/or accesstechnologies to ensure “fairness”. In another example, the duration ofthe validity period may be established from system informationtransmitted by the base station or from other signalling previouslyreceived from the base station, for example during initial connectionestablishment for the terminal device. In yet other examples, theduration of the validity period for a given configuration setting may beselected by the base station and communicated to the terminal device,for example in association with the indication of the configurationsetting transmitted from the base station to the terminal device in stepS4. This can allow for more flexible operation. For example, if themeasurement reports received from the terminal device in step S2indicate very little radio usage in the second frequency band, the basestation may determine a relatively long validity period should be used,whereas if the measurement reports received from the terminal device instep S2 indicate relatively high radio usage in the second frequencyband, the base data may determine a relatively short validity periodshould be used. That is to say, the validity period may be determined bytaking account of the degree of radio traffic in the second frequencyband. In some examples the duration of the validity period may begreater than an amount selected from the group comprising: 0.1 seconds;1 second; 2 seconds; 3 second; and 5 seconds and/or less than an amountselected from the group comprising: 1 hour, 1 minute, 10 seconds; and 5seconds. However, the specific values for the validity period may beselected according to the implementation at hand. In general, a longervalidity period will reduce the frequency with which the terminal deviceshould measure radio usage across the second frequency band and willreduce the associated signalling overhead, whereas a shorter validityperiod will reduce the extent to which communications between the basestation and the terminal device interfere with other devices trying toaccess the shared resources of the second frequency band.

In step S7 the base station starts communicating with the terminaldevice using the primary carrier and the secondary carrier configured inaccordance with the current configuration setting for the secondarycomponent carrier. This may be done based on established carrieraggregation techniques and using previously-proposed techniques formaking use of unlicensed frequency spectrum. The communication of databetween the base station and the terminal device may continue asschematically indicated by the arrow below the representation of step S7in FIG. 5.

In step S8 the terminal device measures channel quality for thesecondary carrier. This is performed in parallel with the ongoingcommunication of data from the base station to the terminal device usingthe primary and secondary carriers. The measurement of channel qualityfor the secondary carrier may be based on established channel qualitymeasurement techniques in wireless telecommunications systems.

In particular, the measurements undertaken in step S8 may correspondwith those undertaken for conventional channel quality indicator (CQI)reporting in LTE wireless communication systems. That is to say, step S8may correspond with the measurements that are already normallyundertaken for conventional CQI reporting on a secondary cell is acarrier aggregation scenario (for example, using sounding referencesymbols). In this regard, and although not shown in FIG. 5, the terminaldevice may report the channel quality measurements back to the basestation to assist the base station in making scheduling decisions forallocating transmission resources to the terminal device on thesecondary carrier in accordance with conventional LTE techniques.

The channel quality measurements of step S8 may continue in parallelwith the ongoing communication of data using the first and secondarycarriers that started in step S7. This may continue until one or otherof two conditions is satisfied, as schematically indicated in step S9.

Thus, step S9 in FIG. 5 indicates that the base station and terminaldevice continue to communicate data using the primary and secondarycarriers in accordance with conventional carrier aggregation techniquesas applied to unlicensed spectrum operation until either (a) thevalidity period established in step S6 expires or (b) the channelquality measurements for the secondary carrier indicate the channelconditions associated with the secondary carrier have fallen below athreshold quality level. The threshold quality level may be determinedaccording to the implementation at hand. For example, the threshold maycorrespond with a level below which the channel quality is considered tobe too poor for supporting data transfer with at least a minimumacceptable data rate, or it may correspond with a level indicative ofthe presence of signals from devices using another radio accesstechnology on the same frequency which would then simply identifypotential interference from or to the other radio access technology.

If either of the relevant events occur, the terminal device assumes theconfiguration setting for the secondary carrier received in step S4 isno longer valid, and the terminal device returns to step S1 of theprocessing represented in FIG. 5. Thus, the terminal device againmeasures radio usage across the unlicensed band (second band) andproceeds to transmit an indication of the measures radio usage to thebase station. Processing may then continue as described above. Thisresults in the base station determining an updated configuration settingfor the secondary carrier in a subsequent iteration of step S3, andcommunicating the updated configuration setting to the terminal devicein a subsequent iteration of step S4, thereby allowing the terminaldevice to configure its LTE transceiver and subsequently receive data onthe secondary carrier in accordance with the updated configurationsetting, and so on, with repeated iterations through the steps of FIG.5.

Thus the approach represented in FIG. 5 provides for asemi-persistent/semi-static secondary cell configuration (e.g. in termsof the transmission resources in the second frequency band which are tobe used for the secondary carrier) to be used when aggregatingunlicensed radio spectrum transmission resources with licensed radiospectrum transmission resources. This approach has been found by theinventors to provide a number of advantages. For example, the approachcan help to conserve terminal device battery power since the terminaldevice can be configured to undertake the measurements of radio usageacross the secondary frequency band which are used by the base stationto determine a suitable configuration setting (e.g. frequency setting)for the secondary carrier only when the existing configuration becomesunusable and/or after the validity period has expired. The use of avalidity period after which the radio usage across the second frequencyband is re-measured by the terminal device and reported to the basestation can help to prevent the wireless telecommunications system fromoverly impacting the ability of other wireless communication systems(e.g. Wi-Fi or Bluetooth or another LTE system) to use the sharedresources of the unlicensed radio spectrum comprising the secondfrequency band.

It will be appreciated the approaches described above may be modified inaccordance with other embodiments of the invention. For example, theorder in which the steps of FIG. 5 are performed may be different inother implementations. For example, steps S5 and S6 may be reversed, orin the event the validity period is fixed, step S6 may be performedbefore step S1.

Furthermore, it will be appreciated that while in the above describedembodiments the base station establishes an indication of radio usageacross the U band based on measurements of channel conditions made bythe terminal device and reported to the base station (in steps S1 andS2), in accordance with other embodiments of the disclosure, the basestation may establish a measure of radio usage in the second frequencyband in a different way. That is to say, in some embodiments of thedisclosure a terminal device need not be involved in measuring andreporting channel conditions used by the base station to select anappropriate carrier configuration setting (i.e. in accordance with someembodiments there may be no steps correspondence with steps S1 and S2described above). For example, the base station may itself measure radiousage at different frequencies across the second frequency band ratherthan, or in addition to, relying on feedback received from one or moreterminal devices.

Furthermore, while the above-described embodiments have focused on animplementation in which a single secondary carrier/Scell is associatedwith the second frequency band, the same principles can be applied whenusing multiple secondary carrier(s)/Scell(s) in the second frequencyband. In this case each of the multiple secondary carrier(s) may beassociated with the same or different validity period, and may beconfigured at the same time or may be staggered.

Furthermore, it will be appreciated that in some example embodiments,step S9 may be modified so that a currently-used component carrierconfiguration becomes invalid only on expiry of its validity period.That is to say, the carrier configuration may, at least so far as theterminal device is concerned, remain valid even if the channel qualitybecomes very poor. In this case the base station may simply choose notto schedule further transmissions for the terminal device until the basestation receives an updated indication of radio usage across the secondcarrier in an iteration of step S2 following expiry of the terminaldevice's validity period, thereby allowing the second carrier to bere-configured. Furthermore, in yet another example, step S9 may bemodified so that a currently-used component carrier configurationbecomes invalid only if the measured channel quality falls below thethreshold level. That is to say, some implementations may not adopt anapproach using a validity period. That is to say, there may be no stepcorresponding to S6.

Furthermore, in the examples described above it is assumed the terminaldevice will consider the secondary carrier configuration to becomeinvalid if either of the conditions of step S9 are met. However, inanother example the terminal device may return to step S1 as describedabove if either of the conditions of step S9 are met, but maynonetheless continue to assume the current configuration setting for thesecondary carrier remains valid until an indication of a newconfiguration setting is received from the base station.

As described above, step S1 is performed in a repeated manner inresponse to one of the conditions of step S9 being met. However, in someexamples step S1 may also be triggered by the base station. For example,the base station may be configured to transmit a message to the terminaldevice to request that the terminal device provides the base stationwith an indication of radio usage in the second frequency band (i.e.request that the terminal device performs steps corresponding to stepsS1 and S2 in FIG. 5). This request may, for example, be made inaccordance with conventional control signalling techniques on theprimary carrier. This can allow the base station to initiate the processof reconfiguring the secondary carrier before the validity periodexpires or the channel conditions fall below an acceptable level.Furthermore, this can be the process by which the base station initiatesstep S1 in a first iteration of the process represented in FIG. 5 (i.e.when it is determined that carrier aggregation using resources in thesecond frequency band is to be commenced for the terminal device).

It will be appreciated that while the above-described embodiments arefocused on a single base station supporting both the primary componentcarrier the secondary component carrier, more generally these could betransmitted from separate base stations. In this regard, thenetwork-side processing in accordance with embodiments of the presentdisclosure may be performed by network infrastructure equipment whichcomprises, for example, one base station or more than one base station,and potentially other network infrastructure equipment elementsaccording to the operating principles of the wireless telecommunicationsnetwork in which the approach is implemented.

It will be appreciated the principles described above may be applied inrespect of a wireless telecommunications system supporting carrieraggregation with secondary component carriers operating in a frequencyband over which the wireless telecommunications system does not haveexclusive control irrespective of whether or not the wirelesstelecommunications system requires an administrative license to operatein the secondary frequency band. That is to say, it will be appreciatedthe terminology “unlicensed” is used herein for convenience to refer tooperation in a band over which the wireless telecommunications systemdoes not have exclusive access. In many implementations this willcorrespond with a license exempt frequency band. However, in otherimplementations the operation may be applied in a frequency band whichis not unlicensed in the strict administrative sense, but which isnonetheless available for shared/opportunistic use by devices operatingaccording to different wireless access technologies (e.g. LTE-based,Wi-Fi-based and/or Bluetooth-based technologies) and/or multiplenetworks operating according to the same technology (e.g. LTE-basedwireless communication systems provided by different network operators).In this regard the terminology such as “unlicensed frequency band” maybe considered to refer generally to a frequency band in which resourcesare shared by different wireless communications systems. Accordingly,while the term “unlicensed” is commonly used to refer to these types offrequency bands, in some deployment scenarios an operator of a wirelesstelecommunications system may nonetheless be required to hold anadministrative license to operate in these frequency bands.

Thus there has been described a method of operating a terminal deviceand a base station in a wireless telecommunications system tocommunicate with one another using a primary component carrier operatingon radio resources within a first frequency band and a secondarycomponent carrier operating on radio resources within a second frequencyband. The terminal device makes measurements of radio usage in thesecond frequency band, e.g. by other devices which are not part of thewireless telecommunications system but which can also use radioresources within the second frequency band. The terminal devicetransmits an indication of the measurements to the base station, and onthe basis if this the base station establishes a configuration settingfor the secondary component carrier, for example in terms of frequencyresources to use for the secondary component carrier. The configurationsetting is associated with a validity period during which the basestation communicates data to the terminal device using the primarycomponent carrier and the secondary component carrier operating inaccordance with its configuration setting. When the validity periodexpires, the terminal device again measures and reports on radio usageso the base station can determine an updated configuration setting forthe secondary component carrier that takes account of any changes inradio usage during the validity period.

Further particular and preferred aspects of the present invention areset out in the accompanying independent and dependent claims. It will beappreciated that features of the dependent claims may be combined withfeatures of the independent claims in combinations other than thoseexplicitly set out in the claims.

Thus, the foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. As will be understood by thoseskilled in the art, the present invention may be embodied in otherspecific forms without departing from the spirit or essentialcharacteristics thereof. Accordingly, the disclosure of the presentinvention is intended to be illustrative, but not limiting of the scopeof the invention, as well as other claims. The disclosure, including anyreadily discernible variants of the teachings herein, define, in part,the scope of the foregoing claim terminology such that no inventivesubject matter is dedicated to the public.

Respective features of the present disclosure are defined by thefollowing numbered paragraphs:

Paragraph 1. A method of operating a terminal device in a wirelesstelecommunications system for communicating with network infrastructureequipment using a primary component carrier operating on radio resourceswithin a first frequency band and a secondary component carrieroperating on radio resources within a second frequency band, wherein themethod comprises the steps: (a) receiving an indication of aconfiguration setting for the secondary component carrier from thenetwork infrastructure equipment; (b) establishing a validity period forthe configuration setting for the secondary component carrier; and (c)receiving data from the network infrastructure equipment using theprimary component carrier and the secondary component carrier operatingin accordance with the configuration setting for the secondary componentcarrier during the validity period for the configuration setting.

Paragraph 2. The method of paragraph 1, further comprising makingmeasurements of radio usage in the second frequency band andtransmitting an indication of the measurements of radio usage in thesecond frequency band to the network infrastructure equipment prior tostep (a).

Paragraph 3. The method of paragraph 2, further comprising determiningif the validity period for the configuration setting for the secondarycomponent carrier has expired, and if so, making measurements of radiousage in the second frequency band and transmitting an indication of themeasurements of radio usage in the second frequency band to the networkinfrastructure equipment.

Paragraph 4. The method of any one of paragraphs 1 to 3, furthercomprising determining if the validity period for the configurationsetting for the secondary component carrier has expired, and if so,releasing the configuration setting.

Paragraph 5. The method of any one of paragraphs 1 to 4, furthercomprising: receiving an indication of an updated configuration settingfor the secondary component carrier from the network infrastructureequipment after the validity period for the configuration setting forthe secondary component carrier has expired; establishing a validityperiod for the updated configuration setting for the secondary componentcarrier; and receiving data from the network infrastructure equipmentusing the primary component carrier and the secondary component carrieroperating in accordance with the updated configuration setting for thesecondary component carrier during the validity period for the updatedconfiguration setting.

Paragraph 6. The method of any one of paragraphs 1 to 5, furthercomprising performing channel quality measurements for the secondarycomponent carrier and determining if the channel quality measurementsindicate the channel quality is below a threshold channel quality, andif so, making measurements of radio usage in the second frequency bandand transmitting an indication of the measurements of radio usage in thesecond frequency band to the network infrastructure equipment.

Paragraph 7. The method of paragraph 6, further comprising: receiving anindication of an updated configuration setting for the secondarycomponent carrier from the network infrastructure equipment aftertransmitting an indication of the measurements of radio usage in thesecond frequency band to the network infrastructure equipment;establishing a validity period for the updated configuration setting forthe secondary component carrier; and receiving data from the networkinfrastructure equipment using the primary component carrier and thesecondary component carrier operating in accordance with the updatedconfiguration setting for the secondary component carrier during thevalidity period for the updated configuration setting.

Paragraph 8. The method of any one of paragraphs 1 to 7, furthercomprising receiving a request from the network infrastructure equipmentto provide the network infrastructure equipment with an indication ofradio usage in the second frequency band, and making measurements ofradio usage in the second frequency band and transmitting an indicationof the measurements of radio usage in the second frequency band to thenetwork infrastructure equipment in response thereto.

Paragraph 9. The method of paragraph 8, further comprising: receiving anindication of an updated configuration setting for the secondarycomponent carrier from the network infrastructure equipment aftertransmitting an indication of the measurements of radio usage in thesecond frequency band to the network infrastructure equipment inresponse to receiving the request from the network infrastructureequipment; establishing a validity period for the updated configurationsetting for the secondary component carrier; and receiving data from thenetwork infrastructure equipment using the primary component carrier andthe secondary component carrier operating in accordance with the updatedconfiguration setting for the secondary component carrier during thevalidity period for the updated configuration setting.

Paragraph 10. The method of paragraph 2, wherein the indication of themeasurements of radio usage in the second frequency band are transmittedto the network infrastructure equipment using transmission resources inthe first frequency band.

Paragraph 11. The method of paragraph 2, wherein the indication of themeasurements of radio usage in the second frequency band are transmittedto the network infrastructure equipment using radio resource control,RRC, signalling.

Paragraph 12. The method of any one of paragraphs 1 to 11, wherein theindication of a configuration setting for the secondary componentcarrier is received from the network infrastructure equipment usingtransmission resources in the first frequency band.

Paragraph 13. The method of any one of paragraphs 1 to 12, wherein theindication of a configuration setting for the secondary componentcarrier is received from the network infrastructure equipment usingradio resource control, RRC, signalling.

Paragraph 14. The method of any one of paragraphs 1 to 13, wherein thesecond frequency band comprises radio resources which are shared withwireless communication devices that are not part of the wirelesstelecommunications system.

Paragraph 15. The method of paragraph 2, wherein communications from thenetwork infrastructure equipment are received by the terminal devicewith a receiver operating in accordance with a first wirelesscommunications operating standard and the measurements of radio usage inthe second frequency band are made with a receiver operating inaccordance with a second wireless communications operating standard thatis different from the first wireless communications operating standard.

Paragraph 16. The method of paragraph 15, wherein the first wirelesscommunications operating standard is a cellular telecommunicationsoperating standard and the second wireless communications operatingstandard is a non-cellular telecommunications operating standard.

Paragraph 17. The method of paragraph 15 or 16, wherein the secondwireless communications operating standard is a wireless local areanetwork, WLAN, operating standard.

Paragraph 18. The method of paragraph 2, wherein the indication of themeasurements of radio usage in the second frequency band transmitted tothe network infrastructure equipment comprises information regarding theuse of radio resources in the second frequency band by another wirelesscommunications device.

Paragraph 19. The method of paragraph 18, wherein the informationcomprises one or more of: an indication of frequency resources used bythe other wireless communications device; an indication of a receivedsignal strength for wireless communications associated with the otherwireless communications device; and an indication of an identifier forthe other wireless communications device.

Paragraph 20. The method of any one of paragraphs 1 to 19, wherein thevalidity period is established in accordance with an operating standardfor the wireless telecommunications system.

Paragraph 21. The method of any one of paragraphs 1 to 20, wherein thevalidity period is established from information received from thenetwork infrastructure equipment in association with the configurationsetting for the secondary component carrier received from the networkinfrastructure equipment.

Paragraph 22. The method of any one of paragraphs 1 to 21, wherein theduration of the validity period is greater than an amount selected fromthe group comprising: 0.1 seconds; 1 second; 2 seconds; 3 second; and 5seconds.

Paragraph 23. The method of any one of paragraphs 1 to 22, wherein theduration of the validity period is less than an amount selected from thegroup comprising: 1 hour, 1 minute, 10 seconds; and 5 seconds.

Paragraph 24. The method of any one of paragraphs 1 to 23, wherein theconfiguration setting for the secondary component carrier comprises anindication of transmission resources to be used for the secondarycomponent carrier.

Paragraph 25. A terminal device for use in a wireless telecommunicationssystem for communicating with network infrastructure equipment using aprimary component carrier operating on radio resources within a firstfrequency band and a secondary component carrier operating on radioresources within a second frequency band, wherein the terminal devicecomprises a controller unit and a transceiver unit configured to operatetogether to: (a) receive an indication of a configuration setting forthe secondary component carrier from the network infrastructureequipment; (b) establish a validity period for the configuration settingfor the secondary component carrier; and (c) receive data from thenetwork infrastructure equipment using the primary component carrier andthe secondary component carrier operating in accordance with theconfiguration setting for the secondary component carrier during thevalidity period for the configuration setting.

Paragraph 26. Circuitry for a terminal device for use in a wirelesstelecommunications system for communicating with network infrastructureequipment using a primary component carrier operating on radio resourceswithin a first frequency band and a secondary component carrieroperating on radio resources within a second frequency band, wherein thecircuitry comprises a controller element and a transceiver elementconfigured to operate together to: (a) receive an indication of aconfiguration setting for the secondary component carrier from thenetwork infrastructure equipment; (b) establish a validity period forthe configuration setting for the secondary component carrier; and (c)receive data from the network infrastructure equipment using the primarycomponent carrier and the secondary component carrier operating inaccordance with the configuration setting for the secondary componentcarrier during the validity period for the configuration setting.

Paragraph 27. A method of operating network infrastructure equipment ina wireless telecommunications system for communicating with a terminaldevice using a primary component carrier operating on radio resourceswithin a first frequency band and a secondary component carrieroperating on radio resources within a second frequency band, wherein themethod comprises the steps: (a) establishing an indication of radiousage in the second frequency band; (b) determining a configurationsetting for the secondary component carrier based on the indication ofradio usage in the second frequency band; (d) establishing a validityperiod for the configuration setting for the secondary componentcarrier; (e) transmitting an indication of the configuration setting forthe secondary component carrier to the terminal device; (f) transmittingdata to the terminal device using the primary component carrier and thesecondary component carrier operating in accordance with theconfiguration setting for the secondary component carrier during thevalidity period for the configuration setting; and (g) determining ifthe validity period for the configuration setting for the secondarycomponent carrier has expired, and if so, repeating steps (a) and (b).

Paragraph 28. Network infrastructure equipment for use in a wirelesstelecommunications system for communicating with a terminal device usinga primary component carrier operating on radio resources within a firstfrequency band and a secondary component carrier operating on radioresources within a second frequency band, wherein the networkinfrastructure equipment comprises a controller unit and a transceiverunit configured to operate together to: (a) establish an indication ofradio usage in the second frequency band; (b) determine a configurationsetting for the secondary component carrier based on the indication ofmeasurements of radio usage in the second frequency band; (d) establisha validity period for the configuration setting for the secondarycomponent carrier; (e) transmit an indication of the configurationsetting for the secondary component carrier to the terminal device; (f)transmit data to the terminal device using the primary component carrierand the secondary component carrier operating in accordance with theconfiguration setting for the secondary component carrier during thevalidity period for the configuration setting; and (g) determine if thevalidity period for the configuration setting for the secondarycomponent carrier has expired, and if so, to again receive from theterminal device an indication of measurements of radio usage in thesecond frequency band made by the terminal device and determine aconfiguration setting for the secondary component carrier based on thereceived measurements of radio usage in the second frequency band.

Paragraph 29. Circuitry for network infrastructure equipment for use ina wireless telecommunications system for communicating with a terminaldevice using a primary component carrier operating on radio resourceswithin a first frequency band and a secondary component carrieroperating on radio resources within a second frequency band, wherein thecircuitry comprises a controller element and a transceiver elementconfigured to operate together to: (a) establish an indication ofmeasurements of radio usage in the second frequency band; (b) determinea configuration setting for the secondary component carrier based on theindication of measurements of radio usage in the second frequency band;(d) establish a validity period for the configuration setting for thesecondary component carrier; (e) transmit an indication of theconfiguration setting for the secondary component carrier to theterminal device; (f) transmit data to the terminal device using theprimary component carrier and the secondary component carrier operatingin accordance with the configuration setting for the secondary componentcarrier during the validity period for the configuration setting; and(g) determine if the validity period for the configuration setting forthe secondary component carrier has expired, and if so, to again receivefrom the terminal device an indication of measurements of radio usage inthe second frequency band made by the terminal device and determine aconfiguration setting for the secondary component carrier based on thereceived measurements of radio usage in the second frequency band.

REFERENCES

-   [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based    radio access”, John Wiley and Sons, 2009-   [2] ETSI TS 136 211 V11.5.0 (2014-01)/3GPP TS 36.211 version 11.5.0    Release 11-   [3] ETSI TS 136 212 V11.4.0 (2014-01)/3GPP TS 36.212 version 11.4.0    Release 11-   [4] ETSI TS 136 213 V11.6.0 (2014-03)/3GPP TS 36.213 version 11.6.0    Release 11-   [5] ETSI TS 136 321 V11.5.0 (2014-03)/3GPP TS 36.321 version 11.5.0    Release 11-   [6] ETSI TS 136 331 V11.7.0 (2014-03)/3GPP TS 36.331 version 11.7.0    Release 11

1: Circuitry of a terminal device that communicates with networkinfrastructure equipment using a primary component carrier operating onradio resources within a first frequency band and a secondary componentcarrier operating on radio resources within a second frequency band,wherein the circuitry comprising: a transceiver; and control circuitry,the control circuitry and the transceiver configured together to:receive an indication of a configuration setting for the secondarycomponent carrier from the network infrastructure equipment; establish avalidity period for the configuration setting; and receive data from thenetwork infrastructure equipment, using the primary component carrierand the secondary component carrier in accordance with the configurationsetting, during the validity period for the configuration setting. 2-3.(canceled) 4: The circuitry of claim 1, wherein the control circuitryand the transceiver are further configured to: measure a radio usage inthe second band; and transmit an indication of the measurements of radiousage in the second band. 5: The circuitry of claim 4, wherein thecontrol circuitry and the transceiver are further configured to:determine whether the validity period has expired; and in a case thatthe validity period is determined to have expired, measure the radiousage in the second band and transmit an indication of the measurementsof radio usage in the second band. 6: The circuitry of claim 1, whereinthe control circuitry and the transceiver are further configured to:determine whether the validity period has expired; and in a case thatthe validity period is determined have expired, release theconfiguration setting. 7: The circuitry of claim 1, wherein the controlcircuitry and the transceiver are further configured to: receive anotherindication, of an updated configuration setting for the second band,after the validity period has expired; establish another validity periodfor the updated configuration setting for the second band; and receivedata using the second band operating in accordance with the updatedconfiguration setting during the another validity period for the updatedconfiguration setting. 8: The circuitry of claim 1, wherein the controlcircuitry and the transceiver are further configured to: perform channelquality measurements for the second band; determine whether the channelquality measurements indicate a channel quality is below a thresholdchannel quality; and in a case that the channel quality measurements aredetermined to indicate that the channel quality is below the thresholdchannel quality, measure a radio usage in the second band and transmitan indication of the measurements of radio usage in the second band. 9:The circuitry of claim 8, wherein the control circuitry and thetransceiver are further configured to: receive another indication of anupdated configuration setting for the second band after transmitting theindication of the measurements of radio usage in the second band;establish another validity period for the updated configuration settingfor the second band; and receive data using the second band operating inaccordance with the updated configuration setting for the second bandduring the another validity period for the updated configurationsetting. 10: The circuitry of claim 1, wherein the control circuitry andthe transceiver are further configured to: receive a request to providean indication of radio usage in the second band; measure a radio usagein the second band; and transmit the indication of the measurements ofradio usage in the second band in response thereto. 11: The circuitry ofclaim 10, wherein the control circuitry and the transceiver are furtherconfigured to: receive another indication of an updated configurationsetting for the second band after transmitting the indication of themeasurements of radio usage in the second band in response to receivingthe request; establish another validity period for the updatedconfiguration setting for the second band; and receive data using thesecond band operating in accordance with the updated configurationsetting for the second band during the another validity period for theupdated configuration setting. 12: The circuitry of claim 4, wherein theindication of the measurements of radio usage in the second band istransmitted using transmission resources in the first band. 13: Thecircuitry of claim 4, wherein the indication of the measurements ofradio usage in the second band is transmitted using radio resourcecontrol (RRC) signaling. 15: The circuitry of claim 1, wherein theindication of the configuration setting for the second band is receivedusing transmission resources in the first band. 16: The circuitry ofclaim 1, wherein the indication of the configuration setting for thesecond band is received using radio resource control (RRC) signaling.17: The circuitry of claim 4, wherein communications are received by theterminal device operating in accordance with a first wirelesscommunications operating standard, and the measurements of radio usagein the second band are made by the terminal device operating inaccordance with a second wireless communications operating standard thatis different from the first wireless communications operating standard.18: The circuitry of claim 17, wherein the first wireless communicationsoperating standard is a cellular telecommunications operating standardand the second wireless communications operating standard is anon-cellular telecommunications operating standard. 19: The circuitry ofclaim 1, wherein the validity period is established in accordance withan operating standard for a wireless telecommunications system. 20: Amethod of operating network infrastructure equipment in a wirelesstelecommunications system for communicating with a terminal device usinga primary component carrier operating on radio resources within a firstfrequency band and a secondary component carrier operating on radioresources within a second frequency band, the method comprising:determining a configuration setting for the secondary component carrierbased on radio usage in the second frequency band; establishing avalidity period for the configuration setting; transmitting anindication of the configuration setting for the secondary componentcarrier to the terminal device; transmitting data to the terminaldevice, using the primary component carrier and the secondary componentcarrier in accordance with the configuration setting, during thevalidity period for the configuration setting. 21: The method of claim20, further comprising: determining whether the validity period for theconfiguration setting for the secondary component carrier has expired;and in a case that the validity period is determined to have expired,determining a new configuration setting based on measured radio usage inthe second frequency band and establishing another validity period forthe new configuration setting. 22: Network infrastructure equipment foruse in a wireless telecommunications system for communicating with aterminal device using a primary component carrier operating on radioresources within a first frequency band and a secondary componentcarrier operating on radio resources within a second frequency band, thenetwork infrastructure equipment comprising: processing circuitryconfigured to: determine a configuration setting for the secondarycomponent carrier based on radio usage in the second frequency band;establish a validity period for the configuration setting; transmit anindication of the configuration setting for the secondary componentcarrier to the terminal device; transmit data to the terminal device,using the primary component carrier and the secondary component carrierin accordance with the configuration setting, during the validity periodfor the configuration setting.